


Of Scientific Interest

by keelywolfe



Series: by any other name [26]
Category: Undertale (Video Game)
Genre: Alternate Universe - Underfell (Undertale), Alternate Universe - Underswap (Undertale), Domestic, M/M, Spicyhoney - Freeform, Underfell Papyrus (Undertale), Underfell Sans (Undertale), Underswap Papyrus (Undertale), Undertale Monsters on the Surface, papcest - Freeform
Language: English
Status: Completed
Published: 2018-10-28
Updated: 2018-10-28
Packaged: 2019-08-08 18:04:17
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,539
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16434215
Author URL: https://archiveofourown.org/users/keelywolfe/pseuds/keelywolfe
Summary: Stretch  needs someone who can help him. He gets Sans....yay?





	Of Scientific Interest

* * *

When Monsters had first left the underground, the feeling had almost been indescribable, particularly for the skeletons who’d only been in this universe for a month. Their first sight of the sun came directly on the heels of learning they were never going home again. At the time, Stretch hadn’t been in much of a position to care. That came later, when the nightmares started to ease their hold. 

The first six months or so had been spent in cheap housing provided by the Human government; they had still been negotiating for asylum and while there had certainly been some wariness if not outright fear, Monsters had certain technical advances that had gone a different way during their banishment than humans. Scientists at least knew a good thing when they saw it.

So, for a while, most of them had lived in cheap manufactured homes and even those had been highly sought after. They’d had to set up a sort of lottery and families had moved in as soon as the paint was dry. Monsters had been so eager to see the sun and they’d been willing to live in whatever was offered. 

By the time they had an official sanctuary the shine had come off that, but money from their various patents and deals had been rolling in by then. New New Home had been carefully designed, every square inch of the land they’d been granted had been utilized, and every Monster family had been given an opportunity for a new home, no pun intended. Most had taken it.

Red was one of the few who stayed in the Oldtown part of New New home, and seriously, Asgore needed to start letting other people name shit.

Where Sans and Papyrus, as well as Blue and himself, had chosen to live together, Red had stayed behind when Edge moved into his new house.

Stretch wasn’t sure why; at the time, Red had only shrugged and said he needed his space, and Stretch hadn’t been on good enough terms with Edge to ask. Bringing it up now seemed like more like ripping off a band-aid just to satisfy his own curiosity, so Stretch let it be. Whatever issues Edge had with his brother, if he wanted to talk about them, he knew where to go. 

Today, though, Stretch needed a favor and he was hoping to catch Red at home; even more hopefully he’d be in a good mood. A text was a no-go. All that would do was give him a heads-up, along with a chance for little bastard to flee, so Stretch figured he’d just stop by. New New Home was small enough that he could shortcut through most of it, anyway, so it wasn’t like he was committing to a hike up Everest or something. 

Besides, if Red agreed, they’d be doing enough heavy lifting later.

The contrast of Red’s house to their own was stark. Grass overgrown through a layer of fallen leaves, no flowers or welcome mat to soften it. The only reason he even had curtains was because Edge had left them. Stretch hadn’t been inside in ages, not since Edge had moved out and started hosting their movie nights in what was now their house.

It was, in a word, unwelcoming, which was also a pretty good word to describe Red. Fucked up worked too, but eh, that was two words and the house wasn’t that bad. 

There might be regret for visiting, later, and it was probably just as well that Stretch wasn’t prone to nausea. He had a pretty good idea of how disastrous his house would be if he lived alone, and Red wasn’t the type to tolerate a cleaning service in his space.

If there were any crawly critters, he was out of here before they could infest him.

Bracing himself, Stretch knocked firmly on the door and waited. Minutes ticked by into five and he tried again, knocking harder. Another five minutes and he was going to give it third times a charm before going for the fuck it option and asking someone else.

When he reached up to knock, the door swung open, his knuckles connecting with air as a voice grumbled, “keep your fucking shirt on, waddaya want…stretch?”

It wasn’t the voice that clued him in, or the clothes, but looking down into a face that was unmarked by a crack threw him. Stretch blinked down at the other skeleton, in black shorts and a red T-shirt but unmarred by any cracks or damage; white eye lights, their teeth as blunt as his own, and he wondered if he’d finally tipped over into crazy.

“sans?” he asked, doubtfully, but then that was sort of correct no matter who it was, wasn’t it?

The lazy smile cleared things up a little more; Red always kinda smiled like he was about to take a bite out of you, Sans was a little less…sharky.

“what’re you doing here?” Stretch asked, warily. He didn’t add what he was thinking but it was probably written on his face as clearly as a dick in sharpie after a sleepover. Sans, wearing Red’s clothes, in the late morning? This _was_ a sleepover and whatever dicks had been involved probably hadn’t been the artsy kind.

“considering the side of the door you’re on, shouldn’t i be asking you that?” Sans yawned. “c’mon in, get off the porch.”

He peered around the door and was relieved to see none of his nightmares had popped to life and settled into the living room. There was a dirty dish or two laying around and the floor could use a vacuum, but it wasn’t even as bad as Stretch managed when Edge was out of town. It still felt uneasy walking inside. “i didn’t know you two were together.”

“we’re not,” Sans sounded amused, climbing up on the sofa and sprawling out. He wiggled his bare toes thoughtfully, “red and i aren’t real interested in your version of happily ever after, but we like to have a good time.”

Yeah, Stretch shouldn’t be touching this subject with a forty-nine and a half foot pole. He didn’t want to know about this, not even a little, and his mouth apparently had other ideas on the subject because he blurted out, “you’ll sleep with that asshole and not me? when I asked, you told me no.”

If anything, Sans only looked more amused, since he was also a special kind of asshole. But then, weren’t they all. “aw, you’re plenty fun, sweetheart. you of all people should know better. i turned you down because i could tell you didn’t really want it. just as well, anyway, seems like you like ‘em a little past waist high.” Sans gave him a narrow look, one that sent prickles up Stretch’s spine because that was the look of someone who saw too much, “that was years ago, why’re you bringing that up now? you okay?”

“yeah,” Stretch said sourly. He was pretty sure it wasn’t a lie. “that therapist of yours is all about digging up shit i don’t want to think about and dangling it in front of my brain. trying to get into your shorts qualifies as something i didn’t ever want to think about again, but here we are lingering on it like a fart in an elevator.”

“she does have a way with the gray matter, especially considering we don’t have any,” Sans agreed. “so let’s open a window and let out the stink. what _do_ you want? red’s at the embassy if you need him. probably.”

“nah, i wanted red but you’ll do.

Sans’s grin went a little sharper and it ratcheted the whole uncanny valley resemblance he had to Red up to an uncomfortable level. “good to know we’re interchangeable.”

“yeah, i don’t need to hear anything about you two interchanging,” Stretch scoffed. That required a bare minimum of alcohol to even toe open the door. “what i need is help shortcutting something. the mass is more than i can handle alone.”

“what the fuck are you trying to move?” Sans sounded bored but that was normal. Stretch knew him too well not to see the glint of rising interest. “and why?”

“it’s a surprise for my hubby and if you come with me, i’ll show you.”

“nope.” It was impressive the way Sans managed to pop the ‘p’ without the benefit of lips. “i need to know if this is worth showering for.”

Stretch told him.

“are you shitting me?” Sans shook his head. “can’t be done.”

“yes, it can, i’ve done the equations.”

“the mass of the water…”

“i took it into account, it isn’t an issue,” Stretch said patiently. “you know i’m never wrong.”

Sans sighed. “your math is never wrong, i’ve seen you do equations in your sleep. you, on the other hand…and there’s always a first time for your creepy mental calculator to fuck up.” He hesitated, then warned, “if this doesn’t work, it’s your mess to clean up. you’re the one who wanted to marry the edgelord.”

“deal,” Stretch grinned at him. Not that he’d doubted for a second that Sans would help. He liked stupid experiments as much as Stretch and the only reason he’d gone to Red first was he’d _known_ Sans would agree. 

Red wasn’t his brother, was nothing like Blue but…he was a Sans. It was good to check on him from time to time, make sure everything was okay. Knowing that he was boning Sans was a little bit of a relief, if Stretch were honest; at least he wasn’t constantly alone. 

Sans stood up with a groan, scratching at his hip where his pelvis was peeking over too-large shorts. “lemme shower and we’ll see what we see.” He paused at the bottom of the stairs, unusually serious. “do me a favor in return? don’t mention to the edgelord that i’m boning his brother.”

“i won’t lie, but i won’t bring it up,” Stretch told him, “i don’t have a bone in this fight.”

“good enough,” Sans shrugged. “it’s up to red to mention it if he wants, as far as i’m concerned.”

“yeaaaaah, so, do you think that’s more along the lines of a snowball’s chance in hell or leaning more towards hell freezing over?”

Sans grinned and held his hand out for a fist bump. “i think i’m too tired to come up with a pun to go with that, but i do know red would be chilly about me doing a big reveal.” He started making his way towards the stairs. “have a seat, don’t smoke in the house.”

Stretch eyed the sofa, “have you two fucked there?”

“not recently,” Sans called down, “can you say the same about yours?”

“i can say mine is scotch-guarded,” Stretch grumbled, and gingerly sat on the edge of the cushion to wait.

* * *

Edge was the planner, he loved his spreadsheets and pie charts, whatever the hell he used. Stretch was more of a fly by the seat of his pants kinda guy and hoped he didn’t end up bare-assed by the end. 

In this case, Stretch wasn’t ashamed to say he cheated. He’d turned on the tracking app on Edge’s phone and kept an eye on it until he was almost home. Then he darted downstairs to the basement and stripped, readying himself for what was to come.

He didn’t have to wait long. Barely, he could hear the front door open and close. Only a few minutes later there were boots on the stairs and Edge calling down. “I have to say, I appreciate your tactics more than I would breadcrumbs. Thank you for leaving the flowers whole rather than scattering the petals.”

“hey, romance ain’t dead but it can be tidy,” Stretch said as Edge came into sight, carrying the roses Stretch had laid out in an arrow to guide him. He swirled his hand through the heated water before raising his dripping fingers in a wave. “what do you think?”

Truth be told, Stretch wasn’t all that confident about this. He thought a hot tub was a little slice of awesome, but he wasn’t sure how Edge would feel about it. Anything that tipped the scale past neutral would be good enough, and hell, it wasn’t like they ever used the basement, anyway. It was finished, the walls painted and the floor tiled, and completely empty, not so much as a cardboard box tucked into a corner.

Until now. now it had a very nice hot tub tucked into a corner, the water steaming warm, with all the appropriate precautions for the humidity taken. 

Probably the basement had been intended as a lab for Red. Probably. Stretch was gonna add that question to the list of ones he’d ask on the tenth of never. But this was his house too, so he figured they could use the basement for something else. His own lab would be a pain in the ass to move and he could just shortcut to it, anyway. 

Usually, Stretch was an expert at reading Edge’s expression, but…right now he seemed oddly blank, his eye lights passive as he carefully set the roses down on the bottom step. “How did you even get this in here?”

“i’ll never tell,” Stretch declared. Taking refuge in silliness was automatic, a longtime source of comfort. “my mouth is sealed, you can’t torture it out of me. sans helped.”

Edge raised a brow bone. “You pried him out of my brother’s bed long enough to help?”

That was one question to check off the never-bring-up list. “why did they even think you didn’t know?”

“I have no idea. If they were trying to keep it a secret, then they should make sure their room isn’t next to mine the next time we are in a hotel,” Edge said dryly. 

“okay, so as much as i would love to have a long discussion about sans and your brother screwing, you haven’t answered my question.” Edge only looked at him and Stretch tried to keep his face from falling, knew his smile was wobbling, “you don’t like it.”

Any growing disappointment was instantly converted to a squawk of surprise when Edge abruptly strode forward and climbed into the tub, clothes and all. His suit was sagging and clinging in an instant as he sloshed through the water to pin Stretch to the side of the tub, straddling his lap.

“Hm,” Edge nuzzled at his jaw, “it seems nice enough.”

“you nut,” Stretch could barely talk through his laughter, giggling harder as Edge licked ticklishly along his cervical vertebrae. 

“Isn’t this what you wanted?” Edge asked, and yeah, there was no way his voice could ever sound anything close to innocent. Sexy as fuck was better anyway. 

“something close to it, yeah.” Stretch struggled to unbutton Edge’s sopping shirt. His bare toes found something that gave him a pause, “are you still wearing your boots?”

“I have more,” Edge ducked his head, his teeth grazed Stretch’s collarbone and abruptly he didn’t care about boots, clothes, or anyone screwing anybody who wasn’t him.

This experiment was getting marked down as a success. 

 

-finis-


End file.
